We were surprised to realize that most genes in the hypothesis-driven candidate gene literature for schizophrenia had been assessed once or twice (76.9%). Given the critical importance of replication in genetic studies of complex traits (Chanock et al., 2007), evaluation of false positives and false negatives is not possible. Positive findings from one or two studies cannot be viewed as secure (particularly given the distorting potential of publication bias) and, conversely, negative findings may not provide confident exclusion.
